1. Field of the Invention
The present invention relates to an organic light emitting diode (OLED) device, and more particularly, to an OLED device with brightness uniformity design.
2. Description of the Related Art
FIG. 1(a) is a schematic top view of a conventional organic light emitting diode device 10. FIG. 1(b) is a cross-sectional view of the organic light emitting diode device 10 in FIG. 1(a) taken along a section line A-A and rotated 180 degrees. Thus, the transparent substrate 11 is at the lower part of the figure. Moreover, the anode layer 13 in FIG. 1(b) is also made of transparent materials, so it is not shown in FIG. 1(a).
As shown in FIG. 1(b), the organic light emitting diode device 10 mainly includes a substrate 11, an anode layer 13, a light emitting layer 15, a cathode layer 17, an anode lead 12 and a cathode lead 16. The anode layer 13 is formed on the substrate 11, the light emitting layer 15 is formed on the anode layer 13, the cathode layer 17 is formed on the light emitting layer 15, the anode wire 12 is connected to the anode layer 13, and the cathode wire 16 is connected to the cathode layer 17.
As shown in FIG. 1(a), the anode lead 12 is connected to a positive input terminal of a power supply, and the cathode lead 16 is connected to a negative input terminal of the power supply. Because the light emitting layer 15 is driven by a current that varies depending upon the resistance values of the anode wire 12 and the cathode lead 16, the brightness of the emitted lights at the region of the light emitting layer 15 farthest away from the positive and negative input terminals of the power supply is darkest, as the resistance value of the lead that the current flows through is largest. The brightness of the emitted lights at the light emitting layer 15 region nearest to the positive and negative input terminals of the power supply is the brightest, because the resistance value of the lead that the current flows through is smallest. Thus, the brightness uniformity of the light emitting layer 15 is inadequate, and thereby the light emitting quality of the OLED device 10 is reduced and the application scope of the OLED device 10 is narrowed.